Mode-Locking and All-Optical Clock Recovery in a Semiconductor Fiber Laser Using Cross-Absorption Modulation in an Electro-Absorption Modulator

Mode-locked fiber lasers have numerous applications in optical communications, sensing, and instrumentation. Semiconductor fiber lasers (SFLs) which are mode-locked via cross-gain modulation (XGM) and/or cross-phase modulation in a semiconductor optical amplifier (SOA) can also be used for all-optical clock recovery (AOCR). AOCR has been demonstrated in erbium-doped fiber lasers that are mode-locked using cross-absorption modulation (XAM) in an electro-absorption modulator (EAM). Recently, it was demonstrated that a mode-locked SFL using XAM in an EAM and described the potential use for AOCR at 10 GHz]. The main limitations of our approach are (1) the "long" output pulses (ap 30 ps) for mode-locked operation; and (2) the recovered clock exhibits a low contrast ratio (4 dB) and supermode noise suppression (25 dB). In this paper, we show that we can improve the quality of the mode-locked output pulses and recovered clock signal from the SFL by using inverse RZ (IRZ) pump signals.